<script type="text/javascript">
function popUpWindow(URL, N, W, H, S) { // name, width, height, scrollbars
	var winleft	=	(screen.width - W) / 2;
	var winup	=	(screen.height - H) / 2;
	winProp		=	'width='+W+',height='+H+',left='+winleft+',top='+winup+',scrollbars='+S+',resizable' + ',status=yes'
	Win			=	window.open(URL, N, winProp)
	if (parseInt(navigator.appVersion) >= 4) { Win.window.focus(); }
}

function popUpTextArea() {
	popUpWindow("popup_textarea.html",'SH1',340,130,'no');
}
</script>

<form id="frmTest" name="frmTest" method="post" action="">
  <div align="center">
    <input type="text" name="tbTest" id="tbTest" />
    <input type="button" name="button" id="button" value="Click Me" onclick="popUpTextArea();"/>
  </div>
</form>